1. Department of Oral Surgery and Stomatology, School of Dental Medicine, University of Berne, Freiburgstrasse 7, PO Box 64, 3010 Berne, Switzerland;
2. Institut Straumann AG, Waldenburg, Switzerland;
3. Department of Periodontics, University of Texas Health Science Center at San Antonio, San Antonio, USA; and
4. Division of Pediatric Dentistry and Structural Biology, Department of Operative Dentistry, School of Dental Medicine, University of Berne, Switzerland;